Filter aid feeder



5, 1952 H. E. MARV'EL 2,584,395

FILTER AID FEEDER Filed g- 6, 1946 3 Sheets-Sheet} I3 2I5' an 9 ,//s+

83 I i I m7 HARVEY E. MARVEL 157 INVENTOR.

m6 I a '29 BY v ATTORNEY I35 v a 33 I26 Feb. 5, 1952 Filed Aug. 16, 1946H. E. MARVEL 2,584,395

FILTER AID FEEDER 3 Sheets-Sheet 2 HARVEY E. MHRVEL.

JNVENTOR.

RTTORNEY Patented Feb. 5, 1952 FILTER AID FEEDER Harvey E. Marvel, FortWayne, Ind., assignor to Bowser, Inc., Fort Wayne, Ind., a corporationof Indiana.

Application August 16, 1946, Serial No. 691,001

16 Claims. (Cl. 2101) This invention relates to a feeder for filter aidused in filtering liquids; in particular, it relates to a feeder-whichis used to precoat the elements vof a filterwith filter aid and to addfilter aid,

during the filtering cycle, to the unfiltered liquid before it entersthe filter to maintain the :porosity of the filter cake.

Various slurry feeding devices have been employed in the past but thesegenerally employ agitators, motors, pumps, etc., which are subject toabrasion by the filter aid, are costly, or consurne power continuously.Most prior art devices are difficult to adjust to supply the high rateof flow of filter aid required for precoating and the the abrasivenessof the filter aid.

It is still another object of this invention to provide a slurry feederhaving no continuously moving parts.

Itis still another object of this invention to provide a slurry feederthat is operated solely by liquidsupplied by the pump. It still anotherobject of this invention to provide a slurry feeder having a visibleindicator .to show when the supply of filter aid is becoming exhausted.

It is still another object of this invention to provide a slurry feederthat can be refilled without interrupting the operation of the filter.

It is "still another object of this invention to provide .visible meansto control the quantity of filter aid flowing from the slurry feeder.

Itis yet-another object of this invention to provideaslurry feederhaving parts that are standard for various capacities of tanks.

These and other objects of the invention will become apparent from astudy of the specificationand the drawings which are attached heretoandlnade a part hereof, and in which:

Figure 1 is an elevation showing the slurry feeder and generalarrangement of the piping and valves.

Figure 2 is a sectional view of the slurry feeder tank cone and theerosion device taken on the line 2-2 of Figure 1.

the head.

Figure 5 is a section of the inlet-outlet manifold taken on the line 5-5of Figure 3.

Figure 6 is a plan view of the erosion apparatus. Y

Figure 7 is a sectional view of the back pressure valve taken on theline l- -i of Figure 2.

Referring to Figures 1, 2 and 3 of the drawings, the numeral Idesignates a cylindrical tank with a conical bottom 3 which terminatesin an opening I at its apex. An inlet-outlet manifold 5 (to be describedlater)' is welded in place to cover the opening I. Legs 8 are welded tothe outside of the cone and support the tank.

A bulls-eye type of sight glass 9 is screwed into a flange ll weldedinto the cylindrical portion of the tank immediately adjacent the cone.

A flange I3 is welded in the cylindrical portion of the tank at theapproximate level of the sight glass and is preferably spaced degreestherefrom. Another flange [5, similar to the flange I3, is welded intothe tank near the top.

and spaced degrees from l3.

A band I! is welded around the outside of the tank at the top andallowed to project above the top of the tank (see Figure 4).

A plurality of pairs of lugs H) are welded about the circumference ofthe band, are equally spaced and carry pins 2| which pass through theeyes of bolts 23. A hold down lug 25 and a washer 2'! pass over each ,ofthe eye bolts and a handwheel 29is screwed on the bolt. These partsclamp the head 3| tightly against the top of the band H. A gasket seat31, preferably rectangular in section, is welded around the head flange35 above the bottom thereof, and a circular band .39 is welded to theexterior of the seat 31 and projects downwardly until it is flush withthe bottom of the flange and projects upwardlyabove the gasket seat sothat it may be engaged by lugs 25.

A gasket 4| is pressed into the groove 43 formed by the head flange, theseat and the band. A liquidtight joint is made between the head andthe-tank by compressing the gasket upon the top of the flange ll byscrewing the handwheels down on the eyebolts, the lugs 25 hooking overthe top of the band 39.

A stud 45 is welded to the top, center of the head and is threaded onits upper end. A crane 41, having a bearing on the tank I, has an arm49'passing over the stud and a handwheel 5|, above the arm, engages thethreads on the stud to raise and lower the head.

A vent pipe 53 having a valve 55 is fixed in the head and communicateswith the tank.

The manifold 5 (Figs. 2, 3 and 5) has a channel 51 entering through theflange 59 and extending upward through a tube iii. The tube is prowhichis disposed at a level slightly above the top of flange 59. The flange54 is smaller thanthe hole 1 in the cone and the flange 66 is largerthan the hole, so that the cone rests on the flange 69 and is welded tothe flange 64. chamber 68 is formed by the wall 69 and tube GI andextends down from flange 66 and tapers into the radius of the metalwhich forms the channel 51. The chamber 68 is connected to an outlet Hin flange 13 which is similar to flange 59.

A I3l with a back pressure valve I33. The main line continues on theoutlet side of the valve through the flange I35, nipple I31 and the teeGaskets 'I4'I seal the flanges on the valve I33 with the flanges I3I'-and I35. Another nipple I43 (Fig. 1) connects the tea I39 to a sightglass I45.

The center outlet on tea I21 is connected with the center connection ofa tea I41 through nipples-I49 and I5I and union I53. The righthandbranch I54leading from the tee I41 (Fig. 3) is connected by means ofnipple I55, elbow 'I51, pipe i 59, gate valve I6I, pipe I63, elbow I65,

60 of the manifold 5 and seats upon a gasket 83 which rests in thegroove 65.

The chamber 3i has a top wall 85, a bottom wall 81, and vertical sideWalls 9| joining them.

'The side walls 9i, as shown in Fig. 6, include diametrically opposed,radially extending sections .93, each of which has its inner end joinedwith or other suitable material is secured to the erosion device byscrews I09 passing through holes in the feeder and engaging the tappedholes IN; The feeder is open at the bottom and is mounted in positionwith its bottom edge approximately V above the top of the flange 39 butbelow the rim thereof.

A U-shaped gasket around the top edge of the feeder and engages theinside wall of the cone 3.

The top wall 85 is circular in plan, as shown in Fig. 6, and projectsbeyond the walls 9I except at the point of juncture with sections 93.The openings 95 are preferably located near the corners formed by thewalls 91 and 85, as is clearly shown in Fig. 2.

A conical-shaped spreader tending circular projection I I1 which restsupon the top wall 85 of the erosion device with the flange II5 extendingdown to about the level of the lower sides of holes 95. A hole H9 at theI j apex of the spreader permits passage of a rod "I2I having a collarI23 welded or pinned just above the spreader and the bottom end'threadedto engage the tapped hole I05 in the exchanger. 1 The top end of the rodextends up near the top discharged by the pump is comprised of the teeI21 which connects through nipple I29 and flange I I I extends I II3hasa downwardly turned flange H5 and an inwardly exnipple I61 and flangeI69 to the flange I at the top of the tank The left-hand branch I (Fig.

3) leading from the tee I41 is connected by means of nipple H I, plugcock I13, nipple 1'15 and flange I11 to thechannel 51 of the manifold 5.

A flange I19 is bolted to the outlet side of the manifold (gaskets I8Ibeing used on both the inlet and outlet sides of the manifold) andnipple I83, gate valve I85 and nipple I61 connect the flange with thetee I89 to form line i90. The central outlet of tee I89 is joined to thecorresponding outlet of tee E39 by nipples I9I and I93 andunion I95. Theremaining branch I95 leading from the tee I89 is comprised of nippleI91, elbow i923 (Fig. 1), nipple I, union 203, pipe 295, gate valve 291,nipple 209, elbow 2II, nipple2 i3 and flange 2I5 and isconnected to thflange I3 at the bottom of the tank.

The back pressure valve I33, as shown in Fig.

plane. A seat 221 is formed on the upper side of the port. The valve 229is comprised of the circular disc 235 of rubber or other suitablematerial, a top metal follower 23I the same diameter as the disc and abottom support 233 having guides 235 engaging the wall of port 225. The

disc, support and follower are assembled into the valve assembly andheld in place by the shoulder stud 231, castellated nut 239 and cotterpin 24I which engages the slots in the nut and passes through a hole inthe lower or threaded portion of the stud.

The cone-shaped bonnet 243 of the valve-I33 has a pilot flange 245entering the bore 222. Directly above the pilot is an outwardlyextending circular flange 241. Suitable fasteners 28I hold the bonnetagainst a gasket 219 on the valve body.

A boss 249 extends a short distance down from the top of the bonnet andanother boss I ex- .tends upward directly above boss 249 and is.threaded on the outside as shown at 253. A hole form a shoulder 263, isscrewed into the hole 255.

The springguide 255 having a smaller diameter 261on the lower end toform a shoulder 269 is provided with a. concentric hole.21I whichreceives the projection 29I of the adjusting screw. A compression spring213 seats at the top upon the shoulder 269 of the guide and at thebottom upon the top follower 23 I around the head of the shoulder stud231.

A look nut 215 holds the adjusting screw in 1 position and cap 211screwed on threads 253 pretension 283 directed upward at an angle andfeeder in the sight glass I45.

through a panel 285 which is mounted by screws 281 on and between two ofthe legs 8. The extension terminates in a knob 289 having a pointer 29Iattached to the back of the knob. Both the knob and the pointer aremovable as a unit over a 90-degree arc to regulate and indicate theposition of the cock on the graduated dial 293 which is fixed to thepanel.

The gate'valve I85 has a similar extension 295 directed upward at anidentical angle to the first extension and also projects through thepanel 285. A knob 291 is fixed on the end of the extension projectingthrough the panel.

Operation The slurry feeder has its inlet I21 connected with a pump andits outlet with a filter through sight glass I45. It is assumed that thecover is open and that the erosion mechanism is in place.

In the preferred operation the pump is started with valves I85 and 201closed and IBI and I13 open and the tank I is filled to the level of thesight glass 9, whereupon the pump is stopped. The object of this step isto prevent a great deal of powder from flowing down into the chamber Thetank is next filled with diatomaceous earth to any desired level belowthe inlet I69. Thereafter the cover 3I is swung over the opening in thetank by means of crane 41 and is lowered by means of the wheel 5| untilgasket II is seated on I1. The clamps are applied and handwheels 29 drawthe cover down.

With the vent valve 55 open, the pump is again started and liquid is fedinto the tank until it issues from the vent. The latter is then closed.If it is not desired to precoat, valve I61 is also closed; but ifprecoating is necessary this valve is left open and, in either case,valve I85 is also opened.

Assuming that precoating is to be carried out, the valves I13 and I85are opened wide and as liquid flows in to I21 and valve I33, the poppet229 lifts against the action of spring 213, which is usually. set toapply from 5 to 15 pounds pressure on the valve, and a differentialpressure is set up across the valve; that is, the pressure in lines I54and I10 exceeds the pressure in line I90: Therefore, liquid will flow byway of line I54 into the top of the tank and will wash powder downwardlyalong cones I01 and H3, out over therim 89 into chamber 68 of themanifold and by way of line I90 to the outlet I39 and thence to thefilter.

At the same time, liquid will fiow through line I10 into chamber BI, outthrough the holes 95 to produce a swirling action underneath theprojecting portion of cone 1 I3 and assist in washing powder down ontothe projection of the bottom 81 and out over the rim 89 into themanifold 68 and to the filter.

When precoating is completed (this is usually evidenced by a clearfiltrate) the valve IBI is closed and the valve I13-is regulated untilthe proper amount of powder feed is attained. This is' determined byobserving the effluent of the The pointer 29I and scale'293 serve toindicate the approximate rate of feed of powder during filtration.

As soon as valve I6I is closed, the erosion device alone provides thepowder feed. The jets of liquid issuing through the orifices or holes 95due to the differential pressure created by valve I33, creates a swirlof liquid about the underside of cone II3, the bottom 81 and-up onto thesurface of cone I01 so as to erode or wash powder down through the spacebetween the cones, across the bottom 81 underneath cone I01 and thenover the rim 89 into the manifold. The powder is then passed by way ofline I90 to tee I26 where it becomes mixed with the liquid issuing fromvalve I33. The powder, being heavier than liquid, settles and is fed outby the erosion device. The major portion of the output of the pump will,of course, flow through valve I33 because the orifices being only aboutan eighth of an inch in diameter and being only four in number cannotpass a very large fiow of liquid.

It should be here noted that in the diatomaceous earth availablecommercially there exists numerous small pellets which would plug ascreen In the instant device however, the balls or pellets are quicklydisposed of either by being broken up in the swirl or by being simplywashed over the rim into the manifold.

Another feature of the device resides in the fact that if a containerhaving wetted diatomaceous earth is allowed to stand for a few hourswithout agitation, the material collects at the bottom of the vessel ina rubbery mass which it is practically impossible to feed. In theinstant device however, when the powder settles on the cones, theorifices being protected by the cones are free from the earth and assoon as the pump is started the jets begin to erode the powder andfeeding is again started. The material has remained in the feeder for aslong as two days without causing it to be disabled. Upon application ofunfiltered liquid under pressure, the feed was established at once andmaintained until the feeder was empty.

In the event the supply of powder reaches the level of the bull's-eyebefore filtration is completed, the valves I13, I85 and I6I are closedwhile valve 201 is opened. A gas line is attached to the vent and valve55 is opened. The contents of the tank are forced out through line I3,2, 209, 205, I91,.I9I, I93 into T I26. The pump is not shut down so thatunfiltered liquid is passing through the T I26 at the same time. Thevalve 201 is closed, the gas line is detached, the cover is then removedand additional powder is added. When the cover has been replaced, liquidis again introduced through valve IBI until it appears at the vent valve55 which is thereupon closed. The valves I85 and I13 are again opened torestore the flow through the eroding device and the feeding of powderproceeds as before.

When the end of the run is reached, the powder remaining in the slurryfeeder may be blown from the tank by applying the gas line again to thevent and by closing valve I13. The gas will force all of the powder andliquid from the tank through the manifold chamber 68 and into thefilter.

To clean the feeder, it is first disconnected from the pump and filterand the cover is removed. The cones and erosion device as a unit maythen be lifted from the tank by means of handle I25 so that it may bewashed down. If desired, the rod I2I may be unscrewed from boss I03 sothat the spreader cone II3 may be removed. These parts may then bewashed and sterilized.

The steps required to reassemble the feeder are obvious.

It should be noted that in the event the rate of powder feed is notheavy enough with valve 113- wide open, additional feed may bev obtainedseer-1,395

by adjusting the screw 259 to increase the pressure of spring 213 on thevalve 229. This increases the differential pressure and, consequently,the rate of flow of liquid through the orifices. The increase invelocity of the jets increases their capacity for eroding powder so thatthe flow will be increased. A reverse eiiect will, of course, beexperienced if the difierent'ial pressure is dropped by decreasing thespring without departing from thespirit of the .invention. Accordingly,applicant does not desire to be limited to the specific embodimentdisclosed herein primarily for purposes of illustration; but instead, hedesires protection falling fairly within the scope of the appendedclaims.

What I claim to be new and desire to protect by Letters Patent oftheUnited States is:

'1. In a filter aid feeder, the combination of a tank having a bottom, aflow line communicating with the tank through the bottom thereof, a

downwardly directed frusto-conical, filter aid supporting baffle, meansfor supporting the bafile across said tank above the bottom thereof,said bafile having an opening "at its lower end, a jet forming devicedisposed below said opening, and means for discharging liquid throughsaid device adjacent the baffle to feed filter aid therefrom into saidflow line. i

2. In a filter aid feeder, the combination of a tank having a bottom, aflow line communicating with the tank through the bottom thereof, adownwardly directed, frusto-conical, filter aid supporting baffle, meansfor supporting the bafiie across said tank above the bottom thereof,said baiile having an opening at its lower end, an upwardly directedcone mounted centrally above said opening and forming with the baffle anannular opening for the discharge of filter aid, a liquid jet formindevice disposed below said opening, and means for discharging liquidthrough said device adjacent the baflle to feed filter aid therefrominto said flow line.

3. In a filter aid feeder, the combination'of a tank having a bottom, aflow line communicating with the tankthrough the bottom thereof, adownwardly directed, frusto-conical, filter aid supporting bafile, means.for supporting the baflle across said tank above the bottom thereof,said baflie having an opening at its lower end, an upwardly directedcone mounted centrally above said opening and forming with the bafileennular opening for the discharge of filter aid, a jet forming devicedisposed below said cone but above the lower edge of said.frusto-conical baffle and adapted to direct jets of liquid tangentiallyof said baifle to create a swirl which will cause filter-aid to be takenfrom said bafiie and carried in suspension by'said liquid, means forsupplying liquid to said device, and means for conveying said liquid andsuspended filteraidto said flow line. r

i. In a filter aid feeding device, the combina conduits in the bottom,:saidinlet conduit terminating inafitting, aijetiforming device havingon the inlet conduit, said device having a radially directed bottomflange terminating in an upwardly directed rim, an invertedfrusto-conical baffle attached to said riin, said baiile terminatingabove said flange but :below said rim and being spaced inwardly from therim, sealing means on the upper end of the baffle adapted to engage andseal against the tank, an upright cone disposed over said device andhaving its lower end disposed in spaced relation with respect to saidbaiiie to provide an annular opening therebetween, and means forsupplying liquid under pressure to said device through said inlet sothat filter aid deposited on the cone and baffle will be washed to theflange and .over the rim thereof into said outlet.

5, In a filter aid feeding device, the combination of a tank having abottom, inlet and outlet conduits in the bottom, said inlet conduitterminating in a fitting, a jet forming device having complementaryfitting adapted to be supported on the first named fitting, said devicehaving a radially directed bottom flange terminating in upwardlydirected rim, an inverted frustofl conical baflle attached to said rim,s id bafile terminating above said flange but below said rim and beingspaced inwardly from the rim, sealing means on the upper end of thebafile adapted to engage and seal against the tank, upright conedisposed over said device and having its lower end disposed in spacedrelation with respect to said baille to provide an annular openingtherebetween, said device comprising 11153318 forming a chamber, meansforming a minating in a fitting, a jet forming device havingcomplementary fitting adapted to be supported on the first namedfitting, said device having a radially directed bottom flangeterminating in an upwardly directed rim, an inverted jirusto-conicalbailie supported in the tank and terminating above said flange but belowsaid rim and being spaced inwardly from the rim,

gentially directed jet forming orifices in said chamber, adjacent saidpanic and above the flange, said orifices being above the level of thelower end of said baffle and adapted to form a swirl. of liquid adjacentsaid cone, and means for supplying liquid under pressure tosaid chamberthrough said inlet so that filter aid deposited on the cone and bafflewill be washed to the flange and over the rim thereof to said outlet.

7. In a .filter aid feed-hig'device, the combination of a, tank having:a bottom, inlet and .outlet conduits in the bottom, :said inletconduitterminating in a fitting, a jet forming device having acomplementary fitting adapted to be supported on the first namedfitting, said fittings being telescopically connectable, said devicehaving a radially directed bottom flange terminating in an upwardlydirected rim, an inverted frustoconical bafile attached to said rim,said bafile terminating above said flange but below said rim and beingspaced inwardly from the rim, sealing means on the upper end of thebafile adapted to engage and seal against the tank, an upright conedisposed over said device and fixed thereto so that said cone, baffleand device are removable as a unit, and having its lower end disposed inspaced relation with respect to said baffle to provide an annularopening therebetween, said device comprising means forming a chamber,means forming a plurality of tangentially directed jet forming orificesin said chamber adapted to form a swirl of liquid adjacent said cone,and means for supplying liquid under pressure to said chamber throughsaid inlet so that filter aid deposited on the cone and baflie will bewashed to the flange and over the rim thereof to said outlet.

8. In a filter aid feeder, the combination of a flow line for unfilteredliquid, means for creating a differential pressure in said line, afilter aid tank, means in said tankupon which the filter aidsettles,means forming an opening in. the

supporting means, liquid jet forming means disposed adjacent theopening, said jet forming means comprising means forming a chamber,means forming a plurality of substantially tangentially directedorifices, a conduit connecting said jet forming means with the flow lineon the high pressure side of said differential pressure means, and adischarge conduit connecting said tank below the opening with the flowline on the low pressure side of said differential pressure means, saidjet forming means being disposed to form a swirl of liquid adjacent saidopening to dislodge the filter aid therefrom into said dischargeconduit.

9. In a filter aid feeder the combination of a flow line for unfilteredliquid, a closed filter aid tank, supporting means in said tank disposedso as to receive the filter aid as it settles, said flow line beingconnected to an outlet conduit for said tank, conduits connecting saidtank, both above and below the supporting means, with a supply of liquidunder pressure, valves in said conduits, means forming an annularopening in said supporting means, liquid jet forming means connected tosaid lower conduit and directed so as to create a swirl of liquid insaid opening for dislodging said filter aid from the supporting meansand passing it through said opening, and said dislodged filter aidpassing to said flow line through said outlet conduit.

10. In a filter aid feeder the combination of a flow line for unfilteredliquid, a closed filter aid tank, supporting means in said tank disposedso as to receive the filter aid as it settles, said flow line beingconnected to an outlet conduit for said tank, inlet conduits connectingsaid tank, both above and below the supporting means, with a supply ofliquid under pressure, valves in said conduits, means forming an annularopening in said supporting means, liquid jet forming means connected tosaid lower inlet conduit and directed so as to create a swirl of liquidin said opening for dislodging said filter aid from the supporting meansand passing it through said opening, and said dislodged filter aidpassing to said fiowline through said outlet conduit, both of said inletconduits cooperating to discharge a heavy flowof filter aid, said lowerconduit and the jet-forming means operating alone to discharge aregulated, lighter flow.

11. In a filter aid feeder the combination of a flow line for unfilteredliquid, means for creating a differential pressure in said line, aclosed filter aid tank, an inverted, frusto-conical supporting bafile insaid tank having upper and lower openings, means for mounting saidbaflle coaxially in the tank so as to receive the filter aid as itsettles, the conical formation of the bafile tending to urge the filteraid toward the lower opening, said fiow line being connected at the lowpressure side of said differential pressure means to an outlet conduitfor said tank, conduits connecting said tank, both above and below thesupporting means, with the flow line, on the high pressure side of saiddifferential pressure means, valves in said conduits, liquid jet formingmeans connected to said lower conduit and directed so as to create aswirl of liquid in said lower opening for dislodging said filter aidfrom the baflle and passing it through said opening, and to said flowline, through said outlet conduit.

12. In a filter aid feeding device, the combination of a tank having abottom, inlet and outlet conduits in the bottom, said inlet conduitterminating in a fitting, a jet forming device having a complementaryfitting adapted to be supported on the first named fitting, said devicehaving a radially directed bottom flange terminating in an upwardlydirected rim, an inverted frusto-conioal baffle supported in the tankand terminating above said flange but below said rim and beingspacedinwardly from the rim, sealing means on the upper endof the baffleadapted to engage and seal against the tank, an upright cone disposedover said device and having its lower end disposed in spaced relationwith respect to said bafiie to provide an annular opening therebetween,said device comprising means forming a chamber, means forming aplurality of tangentially directed jet forming orifices in said chamber,adjacent said baflie and flange, said orifices being adapted to form aswirl of liquid adjacent said baffle, and means for supplying liquidunder pressure to said chamber through said inlet so that filter aiddeposited on the cone and baflie will be washed to the flange and overthe rim thereof to said outlet.

13. In a filter aid feeding device, the combination of a tank having abottom, inlet and outlet conduits in the bottom, said inlet conduitterminating in a fitting, a jet forming device having a complementaryfitting adapted to be supported on the first named fitting, said devicehaving a radially directed bottom flange terminating in an upwardlydirected rim, an inverted frustoconical bafiie supported in the tank andterminating above said flange but below said rim and being spacedinwardly from the rim, means forming a seal between the upper end of thebafiie and the tank, an upright cone disposed over said device andhaving its lower end disposed in spaced relation with respect to saidbafile to provide an annular opening therebetween, said devicecomprising means forming a chamber, means forming a plurality oftangentially directed jet forming orifices in said chamber, adjacentsaid bafile and flange, said orifices being adapted to form a swirl ofliquid adjacent said baffle, and means for supplying liquid underpressure to said chamber through said inlet so that filter aid depositedon the cone and baiile will be washed to the flange and over the rimthereof to said outlet.

14. In a device for feeding into a liquid, a finely divided, granularfilter aid which is heavier than and insoluble in the liquid but iscapable of suspension therein, the combination of a tank, a perforatemeans disposed within said tank above the bottom thereof to form asingle bottom chamher and to support a body of said filter aid, an inletand an outlet for liquid communicating with each other through saidsingle bottom chamber of said tank below said perforate means, andliquid jet forming means communicating with said inlet, disposedadjacent said perforate means and comprising means for creating a swirlof liquid in contact with the body of filter aid adjacent it tocontinuously erode granules of filter aid therefrom for movementdownwardly through the perforate means into suspension in the liquidflowing to the outlet.

15. In a device for feeding into a liquid, 2, finely divided, granularfilter aid which is heavier than and insoluble in the liquid but iscapable of suspension therein, the combination of a tank, a perforatemeans disposed within said tank above the bottom thereof to form asingle bottom chamber and to support a body of said filter aid, an

16. In a device for feeding into a liquid. 9. finely divided, granularfilter aid which is heavier than and insoluble in the liquid but iscapable of suspension therein, the combination of a tank, a. perforatemeans disposed within said tank above the bottom thereof to form asingle bottom chamber and to support a body of said filter aid, an inletand an outlet for liquid communicating with each other through saidsingle bottom cham ber of said tank below said perforate means, and

hydraulic means communicating with said inlet, disposed adjacent saidperforate means and acting upon said body of filter aid to continuouslyerode granules therefrom for movement downwardly through the perforatemeans into suspension in the liquid passing to said outlet, saidperforate means comprising filter aid supporting surface means definingan opening and converging thereon, said surface means being disposed ata slope to urge filter aid toward the opening to replace that removed bysaid hydraulic means.

HARVEY E. MARVEL.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 423,773 Jewell Mar. 18, 1890667,559 Neubauer Feb. 5, 1901 1,276,653 Herbert et a1. Aug. 20, 19181,409,248 Sevcik Mar. 14, 1922 2,142,947 Kretzschmar et a1. Jan. 3, 19392,216,921 Marvel Oct. 8, 1940 2,227,646 Hillman Jan. 7, 1941 2,462,886Morrow Mar. 1, 1949

